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Date: Thu, 22 May 2025 10:17:16 -0700 (PDT)
To: cygwin@cygwin.com
Subject: Re: fork error when trying to call VirtualAlloc with size==0
In-Reply-To: <2574093e-922e-c9a3-2be0-c7cb2a829106@jdrake.com>
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From: Jeremy Drake via Cygwin <cygwin@cygwin.com>
Reply-To: Jeremy Drake <cygwin@jdrake.com>
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On Wed, 21 May 2025, Jeremy Drake via Cygwin wrote:

> On Wed, 21 May 2025, Jeremy Drake via Cygwin wrote:
>
> > the child to not be very fruitful, but maybe there's some debugging to be
> > done there
>
> Well, found the bug that results in a 0 size.  size is a DWORD, but
> mb.RegionSize is 0x200000000.  mb.RegionSize is SIZE_T, but I figure
> size_t is appropriate.

I've sent a patch
https://cygwin.com/pipermail/cygwin-patches/2025q2/013726.html for review.
Now I get the correct error message:
    0 [main] rustc 1569 child_info_fork::abort: unable to remap
\??\V:\rust\rustc-nightly-src\build-MSYS\x86_64-pc-cygwin\stage0-rustc\release\deps\tracing_attributes-0e8ab81319ad49f1.dll
(using V:\rust\rustc-nightly-src\build-MSYS\x86_64-pc-cygwin\stage0-rustc\release\deps\tracing_attributes-0e8ab81319ad49f1.dll)
to same address as parent (0x2090000) - try running rebaseall

Ultimately, playing whack-a-mole in a 64-bit address space hoping that the
DLL will load in the same place as the parent is an exercise in futility,
especially in only 6 attempts.

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